Trigger frame recovery

ABSTRACT

Methods, computer readable media, and wireless apparatuses are disclosed for trigger frame recovery. An apparatus of a wireless device is disclosed. The apparatus comprising processing circuitry configured to: encode a trigger frame comprising a resource allocation for one or more stations, where the trigger frame comprises a network allocation vector (NAV) duration. The processing circuitry may be further configured to configure the wireless device to transmit the trigger frame to the one or more stations. The processing circuitry may be further configured to configure the wireless device to contend for the wireless medium a first time, encode a retransmission of the trigger frame, and configure the wireless device to transmit the retransmission of the trigger frame to the one or more stations, if a frame is not received from the one or more stations in response to the trigger frame before a trigger frame timeout duration.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.15/197,317, filed Jun. 29, 2017, which claims the benefit of priorityunder 35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No.62/294,353, filed Feb. 12, 2016, each of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

Embodiments pertain to wireless networks and wireless communications.Some embodiments relate to wireless local area networks (WLANs) andWi-Fi networks including networks operating in accordance with the IEEE802.11 family of standards. Some embodiments relate to IEEE 802.11ax.Some embodiments relate to methods, computer readable media, andapparatus for trigger frame recovery.

BACKGROUND

Efficient use of the resources of a wireless local-area network (WLAN)is important to provide bandwidth and acceptable response times to theusers of the WLAN. However, often there are many devices trying to sharethe same resources and some devices may be limited by the communicationprotocol they use or by their hardware bandwidth. Moreover, wirelessdevices may need to operate with both newer protocols and with legacydevice protocols.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 illustrates a WLAN in accordance with some embodiments;

FIG. 2 illustrates a trigger frame in accordance with some embodiments;

FIG. 3 illustrates a method for recovery methods for a trigger frame inaccordance with some embodiments;

FIG. 4 illustrates a method for recovery methods for a trigger frame inaccordance with some embodiments;

FIG. 5 illustrates a method for recovery methods for a trigger frame inaccordance with some embodiments;

FIG. 6 illustrates a recovery method for trigger frame in accordancewith some embodiments;

FIG. 7 illustrates a recovery method for trigger frame in accordancewith some embodiments; and

FIG. 8 illustrates a block diagram of an example machine upon which anyone or more of the techniques (e.g., methodologies) discussed herein mayperform.

DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 illustrates a WLAN 100 in accordance with some embodiments. TheWLAN may comprise a basis service set (BSS) 100 that may include amaster station 102, which may be an AP, a plurality of high-efficiency(HE) (e.g., IEEE 802.11ax) stations 104, and a plurality of legacy(e.g., IEEE 802.11n/ac) devices 106.

The master station 102 may be an AP using one of the IEEE 802.11protocols to transmit and receive. The master station 102 may be a basestation. The master station 102 may use other communications protocolsas well as the IEEE 802.11 protocol. The IEEE 802.11 protocol may beIEEE 802.11ax. The IEEE 802.11 protocol may include using orthogonalfrequency division multiple-access (OFDMA), time division multipleaccess (TDMA), and/or code division multiple access (CDMA). The IEEE802.11 protocol may include a multiple access technique. For example,the IEEE 802.11 protocol may include space-division multiple access(SDMA) and/or multiple-user multiple-input multiple-output (MU-MIMO).The master station 102 and/or HE station 104 may use one or both ofMU-MIMO and OFDMA. There may be more than one master station 102 that ispart of an extended service set (ESS). A controller (not illustrated)may store information that is common to the more than one master station102. The controller may have access to an external network such as theInternet.

The legacy devices 106 may operate in accordance with one or more ofIEEE 802.11 a/b/g/n/ac/ad/af/ah/aj, or another legacy wirelesscommunication standard. The legacy devices 106 may be STAs or IEEE802.11 STAs. The HE stations 104 may be wireless transmit and receivedevices such as cellular telephone, smart telephone, handheld wirelessdevice, wireless glasses, wireless watch, wireless personal device,tablet, or another device that may be transmitting and receiving usingthe IEEE 802.11 protocol such as IEEE 802.11 ax or another wirelessprotocol such as IEEE 802.11 az. In some embodiments, the HE stations104, master station 102, and/or legacy devices 106 may be termedwireless devices. In some embodiments the HE station 104 may be a “groupowner” (GO) for peer-to-peer modes of operation where the HE station 104may perform some operations of a master station 102.

The master station 102 may communicate with legacy devices 106 inaccordance with legacy IEEE 802.11 communication techniques. In exampleembodiments, the master station 102 may also be configured tocommunicate with HE stations 104 in accordance with legacy IEEE 802.11communication techniques.

In some embodiments, a HE frame may be configurable to have the samebandwidth as a channel. The bandwidth of a channel may be 20 MHz, 40MHz, or 80 MHz, 160 MHz, 320 MHz contiguous bandwidths or an 80+80 MHz(160 MHz) non-contiguous bandwidth. In some embodiments, the bandwidthof a channel may be 1 MHz, 1.25 MHz, 2.03 MHz, 2.5 MHz, 5 MHz and 10MHz, or a combination thereof or another bandwidth that is less or equalto the available bandwidth may also be used. In some embodiments thebandwidth of the channels may be based on a number of activesubcarriers. In some embodiments the bandwidth of the channels aremultiples of 26 (e.g., 26, 52, 104, etc.) active subcarriers or tonesthat are spaced by 20 MHz. In some embodiments the bandwidth of thechannels are 26, 52, 104, 242, etc. active data subcarriers or tonesthat are space 20 MHz apart. In some embodiments the bandwidth of thechannels is 256 tones spaced by 20 MHz. In some embodiments a 20 MHzchannel may comprise 256 tones for a 256 point Fast Fourier Transform(FFT). In some embodiments, a different number of tones is used.

A HE frame may be configured for transmitting a number of spatialstreams, which may be in accordance with MU-MIMO. In some embodiments, aHE frame may be configured for transmitting in accordance with one orboth of OFDMA and MU-MIMO. In other embodiments, the master station 102,HE station 104, and/or legacy device 106 may also implement differenttechnologies such as code division multiple access (CDMA) 2000, CDMA2000 1×, CDMA 2000 Evolution-Data Optimized (EV-DO), Interim Standard2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856(IS-856), Long Term Evolution (LTE), Global System for Mobilecommunications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSMEDGE (GERAN), IEEE 802.16 (i.e., Worldwide Interoperability forMicrowave Access (WiMAX)), BlueTooth®, WiMAX, WiGig, or othertechnologies.

Some embodiments relate to HE communications. In accordance with someIEEE 802.11ax embodiments, a master station 102 may operate as a masterstation which may be arranged to contend for a wireless medium (e.g.,during a contention period) to receive exclusive control of the mediumfor an HE control period. In some embodiments, the HE control period maybe termed a transmission opportunity (TXOP). The master station 102 maytransmit a HE master-sync transmission, which may be a trigger frame orHE control and schedule transmission, at the beginning of the HE controlperiod. The master station 102 may transmit a time duration of the TXOPand channel information. During the HE control period, HE stations 104may communicate with the master station 102 in accordance with anon-contention based multiple access technique such as OFDMA and/orMU-MIMO. This is unlike conventional WLAN communications in whichdevices communicate in accordance with a contention-based communicationtechnique, rather than a multiple access technique. During the HEcontrol period, the master station 102 may communicate with HE stations104 using one or more HE frames. During the HE control period, the HESTAs 104 may operate on a channel smaller than the operating range ofthe master station 102. During the HE control period, legacy stationsrefrain from communicating.

In accordance with some embodiments, during the master-sync transmissionthe HE STAs 104 may contend for the wireless medium with the legacydevices 106 being excluded from contending for the wireless mediumduring the master-sync transmission or TXOP. In some embodiments thetrigger frame may indicate an uplink (UL) UL-MU-MIMO and/or UL OFDMAcontrol period. In some embodiments, the trigger frame may indicate aportions of the TXOP that are contention based for some HE station 104and portions that are not contention based.

In some embodiments, the multiple-access technique used during the HEcontrol period may be a scheduled OFDMA technique, although this is nota requirement. In some embodiments, the multiple access technique may bea time-division multiple access (TDMA) technique or a frequency divisionmultiple access (FDMA) technique. In some embodiments, the multipleaccess technique may be a space-division multiple access (SDMA)technique.

In example embodiments, the HE device 104 and/or the master station 102are configured to perform the methods and operations herein described inconjunction with FIGS. 1-7.

FIG. 2 illustrates a trigger frame 200 in accordance with someembodiments. The trigger frame 200 may be a HE trigger frame 200. Thetrigger frame 200 may be a UL MU data trigger frame. The trigger frame200 may be a DL MU data trigger frame. The trigger frame 200 may be a MUblock acknowledgement (BA) frame. The trigger frame 200 may be a MUrequest-to-send (RTS) frame. The trigger frame 200 may be a beamformingreport trigger.

The trigger frame 200 comprises a preamble 202 and media access control(MAC) 204. The preamble 202 comprises a legacy portion 206 and a HEportion 208. The legacy portion 206 comprises a legacy length 210 field.For example, the legacy length 210 field may be a field of ahigh-throughput (HT) header that includes a (HT) length of 18 bits thatindicates the number of bytes of the physical layer convergence protocol(PLCP) frame. The legacy portion 206 may have additional legacy lengths210 associated with different IEEE 802.11 protocols.

The HE portion 208 may comprise a HE preamble length 212 and a BSS color213. The HE preamble length 212 field may be a length in the HE-SIG-A(not illustrated) which may be 7 bits and indicate a number of bytes.The MAC 204 may include a NAV duration 214 and a schedule 216. The NAVduration 214 may indicate a length field. For example, the length fieldmay be associated with a UL or DL TXOP that the trigger frame 200 maystart. The schedule 216 field may be an indication of resourceallocations for one or more HEW stations 104. One or more of the legacylength 210 field, the HE preamble length 212 field, and/or the NAVduration 214 field may indicate a length or duration that begins afterthe trigger frame 200 for other wireless devices to set a NAV that arenot referenced in the schedule 216.

The BSS color 213 may be a color of a BSS 100. In some embodiments, BSScolor 213 may be used to indicate that a HE station 104 and/or masterstation 102 should decode the MAC portion of the frame even if the BSScolor 213 does not match a BSS color 213 of the BSS that the HE station104 is attached to.

FIG. 3 illustrates a method 300 for recovery methods for a trigger frame310 in accordance with some embodiments. Illustrated in FIG. 3 is time308 along a horizontal axis, transmitter 306 along a vertical axis,operation 350 along the top, and durations 330 along the top. AP 302 maybe a master station 102. The STAs 304 may be HE station 104. The AP 302may be a HE station 104.

The method 300 begins at operation 352 with the AP 302 transmittingtrigger frame 310. The trigger frame 310 may include a NAV duration 370field and a schedule 372 field. The NAV duration 370 field may indicateNAV duration 336 that the AP 302 is setting for responses 312 and MU-BA314.

The AP 302 may be granted a TXOP after contending for the wirelessmedium (not illustrated), transmitting the trigger frame 310, andreceiving a response 312. The TXOP may last up to the TXOP limit 332.The AP 302 may continue the TXOP past the NAV duration 336 withoutcontending for the medium up to the TXOP limit 332, which may extend toa time 335.

The NAV duration 370 field may extend further past time 334 to permitadditional UL or DL operations. The schedule 372 field may include aresource allocation and transmission parameters for one or more of theSTAs 304 to use to transmit UL data 312. In example embodiments, theschedule 372 field includes a resource allocation for STA2 304.2, STA3304.3, and STA4 304.4. STA2 304.2, STA 304.4 receive the trigger frame310. STA3 304.3 does not successfully decode the trigger frame 310. Thetrigger frame 310 may be a multi-user (MU) block acknowledgement request(BARXMU-BAR) trigger frame, MU request-to-send (RTS) (MU-RTS) triggerframe, beamforming request trigger frame, a beamforming report polltrigger frame, or a MU uplink (UL) data trigger frame.

The method 300 continues at operation 354 with STA2 304.2 and STA4 304.4waiting a duration before transmitting. The duration may be a shortinterframe space (SIFS) or another duration.

The method 300 continues at operation 356 with STA2 304.2 and STA4 304.4transmitting response to TF 312.2, 312.4, respectively. The AP 302receives the response to TF 312.2, 312.4. Upon receiving a response toTF 312, the AP 302 is granted the TXOP, which may continue for up totime 335. The AP 302 may determine that the response to TF 312.2, 312.4is an acknowledgment of the trigger frame 310 since the response to TF312.2, 312.4 is in accordance with the schedule 372. The AP 302 mayreceive just one of the responses to TF 312.2, 312.4 to consider theresponse to TF 312 as an acknowledgment of the trigger frame 310.

The response to TF 312 may be a response to the trigger frame 310 inaccordance with the type of trigger frame. For example, in response to aUL MU data trigger frame, the response to TF 312 may be UL data. Inresponse to a MU-BA trigger frame, the response to TF 312 may be BAs offrames the AP 302 transmitted to the STAs 304. In response to a MU-RTStrigger frame, the response to TF 312 may be MU-clear-to-send (CTS). Inresponse to a beamforming report trigger frame, the response to TF 312may be beamforming reports that may be transmitted in MU fashion orsequentially.

The method 300 optionally continues at operation 358 with the AP 302waiting a duration before transmitting. The duration may be a SIFS oranother duration.

The method 300 optionally continues at operation 360 with the AP 302transmitting MU-BA 314. The MU-BA 314 may be received by STA2 304.2 andSTA4 304.4. Operations 358 and 360 may be optional because the AP 302may not need to acknowledge the response to TF 312, e.g. if the responseto TF 312 is MU-BA. In some embodiments, the duration of MAC duration336 may be short to include only the response to TF 312. At time 334,the AP 302 may continue the TXOP by transmitting after operation 360(e.g., up until TXOP limit 332 to time 335).

FIG. 4 illustrates a method 400 for recovery methods for a trigger frame412 in accordance with some embodiments. Illustrated in FIG. 4 is time408 along a horizontal axis, transmitter 406 along a vertical axis,operations 450 along the top, durations 330 along the top, and frequency409 along a vertical.

The AP 402 may be a master station 102. In some embodiments the AP 402is a HE station 104. STAs 404 are stations in a same BSS and may beassociated with the AP 402. OBSS STA4 405 may be a station that isassociated with a different BSS and not associated with the AP 402. Thechannels 411 may be channels as described herein. The channels 411 mayoverlap in some embodiments. Legacy STA3 407 may be a legacy station 106that may be associated with the AP 402 or may be an OBSS legacy station106 in some embodiments. STA4 405 may a HE station 104 that isassociated with a different AP 402 that overlaps with the BSS of the AP402. STA5 404.5 may be a HE station 104 that is part of the same BSS asthe AP 402, but is not indicated in the trigger frame 412.

The method 400 begins at operation 452 with the AP 402 contending 410for the wireless medium. For example, the AP 402 may contend 410 for thechannel 411.1 by waiting a period of time in accordance with a backoffprocedure to acquire the channel and then wait until the medium is idlefor a distributed interframe space (DIFS) duration until attempting totransmit on the channel 411.

The method 400 may continue at operation 454 with the AP 402transmitting a trigger frame 412 to STA1 1 404.1 and STA2 404.2. Thetrigger frame 412 comprises a NAV duration 470 and a schedule 472. TheNAV duration 470 indicates how long the AP 402 is attempting to use thewireless medium. If the trigger frame 410 is success and the AP 402 isgranted a TXOP, then the AP 402 must operate with a TXOP limit 435. Forexample, a STA 404 may determine a duration based on a modulation andcoding scheme (MCS) and the NAV duration 470. In some embodiments, theNAV duration 470 is termed a NAV length where the duration may bedetermined based on air parameters such as the MCS.

In some embodiments, the trigger frame 412 is received by the legacySTA3 407 and the OBSS STA4 407, but not by STA1 404.1 and STA2 404.2.Legacy STA3 407 may defer based on a legacy length 210 in a legacypreamble portion of the trigger frame 412. The duration that legacy STA3407 defers for may be the same or longer than duration of NAV duration470. The OBSS STA4 405 may defer based on the legacy length 210, or ifOBSS STA4 405 is a HE station 104, the HE preamble length 212 or the NAVduration 214.

Both legacy STA3 407 and OBSS STA4 405 may have received the triggerframe 412 and set their NAVs, e.g., NAV of legacy STA3, OBSS STA4, andSTA5 420 may be set to time 434 which is the ending of the NAV duration470 set by the trigger frame 412.

In some embodiments, OBSS STA4 405 may determine based on the BSS color213 (FIG. 2) of the trigger frame 412 that OBSS STA4 405 should decodethe MAC portion of the trigger frame 412. The BSS color 213 may indicatethat the BSS color is not the BSS color of the BSS of the OBSS and thatOBSS STA4 405 should decode the MAC portion of the trigger frame 412.The trigger frame 412 may be a MU-RTS that is carried in the HE format.

The method 400 continues at operation 456 with the AP 402 waiting for aresponse to the trigger frame 412 from time 438 to time 439. The AP 402determines a timeout at time 439. The AP 402 may wait a trigger frametimeout duration before determining that a timeout has occurred. The AP402 may receive other packets during this time that are not responses tothe trigger frame 412, and the AP 402 will still timeout 418 at time439, which may be the trigger timeout. The trigger timeout 418 may equal(=) (short interframe space) SIFS time+slot time+a receive physicalstart delay (if preamble decoding is needed), where the STAs 404 wouldhave waited SIFS before responding, the slot time is a duration of aslot for the backoff system, and receive physical start delay is thedelay that occurs between the time of receiving the physical header ofthe response and receiving an indication that the physical header isbeing read. The length of the HE PHY header for HE trigger based PPDUsmay be added to the trigger timeout 418 if the AP 402 does not decodethe HE PHY header for the response. The trigger timeout 418 may be howlong the AP 402 waits for a response to the trigger frame 412 until theAP 402 determines there is not a response to the trigger frame 412.

The time 438 when the trigger timeout 418 begins may be a time when theAP 402 receives an indication that the trigger frame 412 transmission iscompleted, e.g. PHYTXEND.confirm primitive. In some embodiments, time438 begins when the trigger frame 412 transmission is completed (e.g,PHYTXEND.confirm primitive is received.) For example, if an indicationis not received of the beginning of receiving a response (e.g,PHY-RXSTART.indication primitive, which may be a primitive from the PHYlayer that indicates that reception of a frame has begun) before thetrigger timeout 418 duration, then the AP 402 concludes that thetransmission of the trigger frame 412 has failed (e.g., STA1 404.1 andSTA2 404.2 did not receive the trigger frame 412 or the AP 402 failed toreceive a response from STA1 404.1 and STA2 404.2). The trigger timeout418 duration begins after PHYTXEND.confirm primitive (e.g., a PHY layerprimitive that indicates that the transmission of a frame has ended) isreceived, in accordance with some embodiments.

In some embodiments, if there is an indication of the start of receivinga frame (e.g., PHY-RXSTART.indication primitive) that occurs during thetrigger timeout 418 duration or interval, which starts from the time anindication is received that the AP 402 has transmitted the trigger frame412 (e.g., PHY-TXEND.confirm primitive), but the AP 402 fails to decodeany valid frame for the response when an indication is given at the endof receiving a frame (e.g., PHY-RXEND.indication primitive, which mayextend past the trigger timeout 418 duration or interval as long as thestart of the receiving of the frame occurs before the trigger timeout418 duration), then the AP 402 assumes the transmission of the triggerframe 412 has failed. The trigger timeout 418 may vary based on the typeof trigger frame 412. For example, a MU-RTS trigger frame 412 may have aspecific timeout value.

In some embodiments, if the trigger frame 412 is an MU-RTS, if anindication that a frame is being received (e.g., PHY-RXSTART.indicationprimitive) does occur during the trigger timeout 418 duration (e.g.,CTSTimeout interval), the AP 402 waits for the corresponding indicationthat the frame has been received (e.g., PHY-RXEND.indication primitive)to determine whether the RTS (or MU-RTS) frame transmission wassuccessful. If the received frame is a valid CTS frame (e.g., from STA1404.1 or STA2 404.2) sent by the recipient of the RTS (or MU-RTS) frame,then the received frame is interpreted as successful response (see FIG.3 response to TF 312), permitting the frame exchange sequence tocontinue. The recognition of anything else, including any other validframe, is interpreted by the AP 402 that the trigger frame 412 hasfailed (e.g., the RTS frame transmission). The AP 402 then contends forthe wireless medium 414 (e.g., the AP 402 invokes its backoff procedureafter time 439 trigger timeout 418 (e.g., PHY-RXEND.indicationprimitive).

The method 400 continues at operation 458 with the AP 402 contending forthe wireless medium 414. The AP 402 may have determined the transmissionof the trigger frame 412 failed and determines to invoke a recoveryprocedure. The AP 402 may have determined that the trigger frame 412 wasa first trigger frame 412 to initiate a TXOP with TXOP limit 435 and nota trigger frame that was transmitted after a TXOP had been granted tothe AP 402 that would be within a TXOP limit 435. The AP 402 initiates abackoff procedure to gain access to the wireless medium. In someembodiments where the trigger frame 412 initiates a TXOP, the AP 402waits a PIFS duration before transmitting the CF-end. In someembodiments, the AP 402 may contend for the wireless medium byperforming a backoff method in accordance with an Enhanced DistributedChannel Access Function (EDCAF).

The method 400 continues at operation 460 with the AP 402 transmitting arecovery response 416. The TXOP limit 435 is no longer applicablebecause the AP 402 failed to be granted a TXOP. In some embodiments, therecovery response 416 may be a contention free (CF)-end. In someembodiments, the AP 402 will only transmit the CF-end if thetransmission is within the NAV duration 470. In some embodiments, the AP402 is required to send a CF-end. In some embodiments, a predeterminedadditional duration must be present between the end of the TXOP 435 andthe end of the transmission of the CF-End for the AP 402 to transmit theCF-end.

In some embodiments, the method 400 continues at operation 457 with STA5104.5 and/or OBSS STA4 405 determining to reset its NAV. STA5 104.5and/or OBSS STA4 405 may have set its NAV based on the trigger frame 412and then determine to reset its NAV depending on the type of triggerframe 412. For a MU-RTS trigger frame 412, the duration to wait beforeresetting the NAV may be (2*a SIFS Time)+(CTS_Time, which may bedetermined based on the PHY format of the MU-RTS frame)+aRxPHYStartDelay(delay to start receiving that a frame is being received)+(2*aSlotTime,where the slot time is the duration of contention window (CW) slot). Insome embodiments, the STA5 104.5 (a station attached to the AP 402, butnot referenced in the trigger frame 412) and/or OBSS STA4 405 maydetermine a different time to reset the NAV with a trigger frame 412type of MU-RTS. The time out for STA5 104.5 and/or OBSS STA4 405 maybegin when a MAC of STA5 104.5 and/or OBSS STA4 405 receives anindication of the end of the reception of the trigger frame 412 (e.g.,PHY-RXEND.indication primitive.)

In some embodiments, a HEW station 104 that used information from anMU-RTS frame (e.g, trigger frame 412) as the most recent basis to updateits NAV setting may reset its NAV if no start of packet receive (e.g.,PHY-RXSTART.indication primitive) is received from the PHY layer duringa period with a duration of that indicates that stations indicated inthe MU-RTS frame are not going to respond (e.g,2×aSIFSTime)+(CTS_Time)+aRxPHYStartDelay+(2×aSlotTime). The duration maybe determined after the HEW station 104 has stopped receive the MU-RTSframe, (e.g., starting when the MAC receives a PHY-RXEND.indicationprimitive corresponding to the detection of the MU-RTS frame.) In someembodiments, the CTS_Time shall be calculated using the length of theCTS frame and the data rate at which the MU-RTS frame used for the mostrecent NAV update was received.

In some embodiments, OBSS STA4 405 may have decoded the trigger frame412 MAC portion based on a BSS color 213 that indicates that the BSScolor is not OBSS, but that the OBSS STA4 405 should decode the MACportion of the trigger frame 412. The OBSS STA4 405 may determine thatthe trigger frame 412 is a MU-RTS frame based on decoding the MACportion of the trigger frame 412. If most recent NAV setting of the OBSSSTA4 405 was based on the trigger frame 412, the OBSS STA4 405 may beconfigured to reset its NAV if no frame is received in response to theMU-RTS, e.g., if no indication of the start of reception of a frame(e.g., PHY-RXSTART.indication primitive is received from the PHY) duringa period with a duration of(2×aSIFSTime)+(CTS_Time)+aRxPHYStartDelay+(2×aSlotTime) starting whenthe MAC receives a PHY-RXEND.indication primitive corresponding to thedetection of the end of the reception of the MU-RTS frame. In someembodiments where the trigger frame 1 512 initiates the TXOP 535, the AP402 waits a PIFS duration before transmitting the CF-end.

The method 400 continues at operation 460 with the AP 402 transmittingthe recovery response 416. The recovery response 416 may be a CF-end.STA1 404.1, STA2 404.2, legacy STA3 407, OBSS STA4 405, and STA5 404.5may receive the recovery response 416 and reset their NAVs.

In some embodiments, the recovery response 416 may be a re-transmissionof the trigger frame 412. The AP 402 may modify the trigger frame 412 toencode the retransmission of the trigger frame 412, e.g., the AP 402 maychange durations or lengths to account for the different time theretransmission of the trigger frame is being transmitted or the AP 402may modify the schedule 472, which may change the NAV duration 470.

The method 400 continues at operation 462 with the AP 402 contending forthe wireless medium. For example, the AP 402 may contend 418 for thechannel 411.1 by waiting a period of time in accordance with a backoffprocedure to acquire the channel and then wait until the medium is idlefor a DIFS duration until attempting to transmit on the channel 411. Insome embodiments, the AP 402 may contend for the wireless medium byperforming a backoff method in accordance with an EDCAF.

The method 400 may continue at operation 464 with the AP 402transmitting a trigger frame retransmission 420 to STA1 1 404.1 and STA2404.2. The trigger frame retransmission 420 comprises a NAV duration 471and a schedule 473. The NAV duration 471 indicates how long the AP 402is attempting to use the wireless medium. If the trigger frameretransmission 420 is success and the AP 402 is granted a TXOP, then theAP 402 must operate with a TXOP limit (not illustrated). The TXOP limit435 was for the trigger frame 412 which unsuccessfully tried to initiatea TXOP. NAV duration 471 may be a different value than NAV duration 471,e.g. the AP 402 may adjust the time for UL data. The schedule 473 may bedifferent than schedule 472 because the AP 402 may adjust times and/orSTAs 404 based on new information or the new situation ofretransmitting. A STA 404 may determine a duration based on a MCS andthe NAV duration 471. In some embodiments, the NAV duration 471 istermed a NAV length where the duration may be determined based on airparameters such as the MCS.

In some embodiments, the trigger frame retransmission 420 is received bythe legacy STA3 407 and the OBSS STA4 407, and by at least one of STA1404.1 and STA2 404.2. Legacy STA3 407 may defer based on a legacy length210 in a legacy preamble portion of the trigger frame retransmission420. The duration that legacy STA3 407 defers for may be the same orlonger than duration of NAV duration 471. The OBSS STA4 405 may deferbased on the legacy length 210, or if OBSS STA4 405 is a HE station 104,the HE preamble length 212 or the NAV duration 471.

Both legacy STA3 407 and OBSS STA4 405 may have received the triggerframe retransmission 420 and set their NAVs, e.g., NAV of legacy STA3,OBSS STA4, and STA5 420 may be set to a duration of the NAV duration471.

In some embodiments, OBSS STA4 405 may determine based on the BSS color213 (FIG. 2) of the trigger frame retransmission 420 that OBSS STA4 405should decode the MAC portion of the trigger frame transmission 420. TheBSS color 213 value may indicate that the BSS color is not the BSS colorof the BSS of the OBSS, and that OBSS STA4 405 should decode the MACportion of the trigger frame retransmission 420. The trigger frameretransmission 420 may be a MU-RTS that is carried in the HE format.

The method may continue with one or more of STA1 404.1, STA2 404.2,and/or STA5 404, which may receive a resource allocation in the schedule473, responding to the TF retransmission 420. When the AP 402 receives aresponse to the TF retransmission 420 then the AP 402 is granted a TXOPthat extends from the end of the TF retransmission 420 to a TXOP limit(not illustrated for the the TF retransmission).

In some embodiments, if the TF retransmission 420 does not receive aresponse then the AP 402 attempt again to retransmit the trigger frame412. In some embodiments, there may be limit of retransmission attemptsbefore the AP 402 stop attempting to retransmit the trigger frame 412for a period of time. In some embodiments, operations 458 and 460 arenot performed.

FIG. 5 illustrates recovery methods 500 for a trigger frame 512 inaccordance with some embodiments. Illustrated in FIG. 5 is time 508along a horizontal axis, transmitter 506 along a vertical axis,operations 550 along the top, durations 530 along the top, and frequency509 along a vertical.

The AP 502 may be a master station 102. In some embodiments the AP 502is a HE station 104. STAs 504 are stations in a same BSS and may beassociated with the AP 502. The channels 511 may be channels asdescribed herein. The channels 511 may overlap in some embodiments.Legacy STA3 507 may be a legacy station 106 that may be associated withthe AP 402 or may be an OBSS legacy station 106 in some embodiments.STA4 505 may a HE station 104 that is associated with a different AP 502that overlaps with the BSS of the AP 502. STA5 504.5 may be a HE station104 that is part of the same BSS as the AP 502, but is not indicated inthe trigger frame 512.

Prior to the method 500, the AP 502 has already transmitted a triggerframe that received a valid response. The AP 502 may have been granted aTXOP with a TXOP limit 537 that extends from time 535 before the method500 begins to time 534. In some embodiments a frame different than atrigger frame initiated the TXOP with a TXOP limit 537.

The method 500 begins at operation 552 with the AP 502 contending 510for the wireless medium. For example, the AP 502 may contend 510 for thechannel 511.1 by waiting a period of time in accordance with a backoffprocedure to acquire the channel and then wait until the medium is idlefor a DIFS duration until attempting to transmit on the channel 511. Insome embodiments, since the AP 502 has already been granted a TXOP, theAP 502 may not contend for the wireless medium or may contend in adifferent manner. For example, the AP 502 may wait a SIFS afterreceiving a valid response to a previous trigger frame or the AP 502 maywait PIFS time.

The method 500 may continue at operation 554 with the AP 502transmitting a trigger frame 1 512 to STA1 1 504.1 and STA2 504.2. Thetrigger frame 512 comprises a NAV duration 570 and a schedule 572. TheNAV duration 570 indicates how long the AP 502 is reserving the wirelessmedium. The time 539 should be less than or equal to time 534.

In some embodiments, the trigger frame 512 is received by the legacySTA3 507 and the OBSS STA4 507, but not by STA1 504.1 and STA2 504.2.Legacy STA3 507, OBSS STA4 505, and STA5 504.5 may have already settheir NAV to time 539 (e.g., the end of the NAV duration 570). In someembodiments, trigger frame 1 512 is not received by STA1 504.1 and STA2504.2.

The method 500 continues at operation 556 with the AP 502 waiting for aresponse to the trigger frame 512 from time 538 to time 539. The AP 502determines a timeout at time 539. The AP 502 may determine the triggertimeout 518 in a same or similar manner as described in conjunction withFIG. 4. The AP 502 may have determined the transmission of the triggerframe 512 failed and determines to attempt to resend the trigger frame 1512.

The method 500 continues at operation 558 with the AP 502 waiting aperiod of time. In some embodiments, the AP 502 based on a PIFS recoverymethod. The channel access function of the AP 502 may transmit after thecarrier sense (CS) mechanism indicates that the medium (e.g., channel511.1) is idle at the transmission PIFS slot boundary as defined by thedistributed coordination function (DCF) timing relations.

Before performing operation 558, the AP 502 may determine whether theduration of operations 558, 560, 562, and 564 are within the TXOP limit537. If the operations 558, 560, 562, and 564 are within the TXOP limit537, then the method 500 continues with operation 558. Otherwise themethod 500 may continue with operation 558, and then a CF-end may betransmitted, in accordance with some embodiments. In some embodiments,prior to transmitting the CF-end the AP 502 will contend for thewireless medium.

The method 500 continues at operation 560 with the AP 402 transmitting atrigger frame 2 516 comprising a length 574 and a schedule 576. Thelength 574 may have a duration of length 574 that extends to time 536.The schedule 576 may include a resource allocation for STA1 504.1 andSTA2 504.2. STA1 504.1 and STA2 504.2 may successively receive triggerframe 2 516. Legacy STA3 507 may receive the trigger frame 2 anddetermine whether to set its NAV based on the length 574 (which may bein a legacy portion of the trigger frame 516 for the legacy STA3 507).The OBSS STA4 505 and/or STA5 504.5 may receive trigger frame 2 516 anddetermine not to reset its NAV based on a timeout from the trigger frame1 512 based on receiving the trigger frame 2 516. In some embodiments,OBSS STA5 505 and/or STA5 504.5 time out and reset their NAVs and thenset their NAV again based on the NAV duration 574.

The method 500 continues at operation 562 with STA1 504.1 and STA2 504.2transmitting response to TF 520.1 and response to TF 520.2,respectively, which may be data, and may be in accordance with theschedule 576.

The method 500 continues at operation 564 with the AP 502 transmitting aMU-BA 522 to STA1 504.1 and STA2 504.2.

FIG. 6 illustrates a recovery method 600 for trigger frame in accordancewith some embodiments. The method 600 begins at operation 602 withencode a trigger frame comprising a resource allocation for one or morestations, wherein the trigger frame comprises a NAV duration. Forexample, AP 402 (FIG. 4) encodes trigger frame 412 with schedule 472 andNAV duration 470. In another example, AP 502 encode trigger frame 1 512with schedule 572 and NAV duration 570.

The method 600 continues at operation 604 with configuring the wirelessdevice to transmit the trigger frame to the one or more stations. Forexample, an apparatus of the AP 402 may configure the AP 402 to transmitthe trigger frame 412. In another example, an apparatus of the AP 502may configure the AP 502 to transmit the trigger frame 512.

The method 600 continues at operation 606 determine whether a frame isnot received from the one or more stations in response to the triggerframe before a trigger frame timeout duration. For example, AP 402 maydetermine that a trigger timeout 418 has occurred. In another example,AP 502 may determine that a trigger timeout 518 has occurred.

If a trigger timeout has not occurred, then the method 500 may continueat operation 610 with continue. For example, after operation 464 the AP402 may receive responses from STAs 404. In another example, AP 502receives response to TF 520.

If the trigger timeout has occurred, then the method 600 continues atoperation 608 with configure the wireless device to contend for thewireless medium, encode a retransmission of the trigger frame, andconfigure the wireless device to transmit the retransmission of thetrigger frame to the one or more stations. For example, AP 402 maycontend for the wireless medium at operation 418 and an apparatus of theAP 402 may configure the AP 402 to transmit the TF retransmission 420.In another example, AP 502 may contend for the wireless medium atoperation 558, and an apparatus of the AP 502 may configure the AP 502to transmit the trigger frame 2 516. In the example of FIG. 5, if the AP502 determines that the NAV duration 574 would extend past TXOP limit537, then the AP 502 may wait until after the TXOP to contend for thewireless medium, encode a retransmission of the trigger frame, andconfigure the wireless device to transmit the retransmission of thetrigger frame to the one or more stations. Additionally, the AP 502 maydetermine to transmit a CF-end, e.g., at operations 558 and 560 if theNAV duration 574 would extend past the TXOP limit 527. The AP 502 maycontend for the wireless medium before transmitting the CF-end.

In the example of FIG. 4, the AP 402 may transmit a CF-end (e.g.,operation 460) before transmitting the TF retransmission 420, and maycontend for the wireless medium before transmitting the CF-end (e.g,operation 458). The method 600 may continue at operation 610 withcontinue.

FIG. 7 illustrates a recovery method 700 for trigger frame in accordancewith some embodiments. The method 700 begins at operation 702 withdecoding a trigger frame from a second wireless device comprising a NAVduration and a resource allocation for each of one or more stations, andwhere the first wireless device is not indicated in the trigger frame.For example, OBSS STA4 405 or STA5 404.5 (FIG. 4) may receive triggerframe 412, where OBSS STA4 405 and STA5 404.5 are not indicated in theschedule 472. In some embodiments, the trigger frame may include a color213 (FIG. 2) that indicates that an OBSS station such as OBSS STA4 405should decode the MAC portion of the trigger frame (e.g., the color 213may have a value of 0, 255, or anther value to indicate to the OBSSstation to decode the MAC portion and use the NAV duration 214 ratherthan a another duration or length indicated in the PHY portion of thetrigger frame.)

The method 700 continues at operation 704 with setting a NAV of thewireless device based on the NAV duration. For example, OBSS STA4 405and STA5 404.5 set a NAV (e.g., NAV of legacy STA3, OBSS STA4, and STA5420) based on the NAV duration 470.

The method 700 continues at operation 706 with is a frame detected bythe first wireless device before a timeout duration, where the timeoutduration is to start after the end of receiving the trigger frame. Forexample, OBSS STA4 405 and STA5 404.5 may not detect a frame before atimeout duration. Alternatively, STA3 304.3 may detect response to TF312.2, 312.4 before a timeout duration after receiving trigger frame310. In some embodiments, the timeout duration is determined based onwhether the trigger frame is a multi-user request-to-send (MU-RTS) oranother type of trigger frame.

The method 700 may continue if no frame is detected before the timeoutduration with resetting the NAV of the first wireless device. Forexample, OBSS STA4 405 and STA5 404.5 may reset their respective NAVsafter a timeout duration (e.g., timeout duration may be at time 439.)The method 700 continues at operation 710 with continue.

If the first wireless device detects a frame before the timeoutduration, then the method 700 continues to operation 710 with continue.

FIG. 8 illustrates a block diagram of an example machine 800 upon whichany one or more of the techniques (e.g., methodologies) discussed hereinmay perform. In alternative embodiments, the machine 800 may operate asa standalone device or may be connected (e.g., networked) to othermachines. In a networked deployment, the machine 800 may operate in thecapacity of a server machine, a client machine, or both in server-clientnetwork environments. In an example, the machine 800 may act as a peermachine in peer-to-peer (P2P) (or other distributed) networkenvironment. The machine 800 may be a master station 102, HE station104, personal computer (PC), a tablet PC, a set-top box (STB), apersonal digital assistant (PDA), a mobile telephone, a smart phone, aweb appliance, a network router, switch or bridge, or any machinecapable of executing instructions (sequential or otherwise) that specifyactions to be taken by that machine. Further, while only a singlemachine is illustrated, the term “machine” shall also be taken toinclude any collection of machines that individually or jointly executea set (or multiple sets) of instructions to perform any one or more ofthe methodologies discussed herein, such as cloud computing, software asa service (SaaS), other computer cluster configurations.

Examples, as described herein, may include, or may operate on, logic ora number of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a machine readable medium. In an example, thesoftware, when executed by the underlying hardware of the module, causesthe hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

Machine (e.g., computer system) 800 may include a hardware processor 802(e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 804 and a static memory 806, some or all of which may communicatewith each other via an interlink (e.g., bus) 808. The machine 800 mayfurther include a display device 810, an input device 812 (e.g., akeyboard), and a user interface (UI) navigation device 814 (e.g., amouse). In an example, the display device 810, input device 812 and UInavigation device 814 may be a touch screen display. The machine 800 mayadditionally include a mass storage (e.g., drive unit) 816, a signalgeneration device 818 (e.g., a speaker), a network interface device 820,and one or more sensors 821, such as a global positioning system (GPS)sensor, compass, accelerometer, or other sensor. The machine 800 mayinclude an output controller 828, such as a serial (e.g., universalserial bus (USB), parallel, or other wired or wireless (e.g.,infrared(IR), near field communication (NFC), etc.) connection tocommunicate or control one or more peripheral devices (e.g., a printer,card reader, etc.).

The storage device 816 may include a machine readable medium 822 onwhich is stored one or more sets of data structures or instructions 824(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 824 may alsoreside, completely or at least partially, within the main memory 804,within static memory 806, or within the hardware processor 802 duringexecution thereof by the machine 800. In an example, one or anycombination of the hardware processor 802, the main memory 804, thestatic memory 806, or the storage device 816 may constitute machinereadable media.

While the machine readable medium 822 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 824.

An apparatus of the machine 800 may be one or more of a hardwareprocessor 802 (e.g., a central processing unit (CPU), a graphicsprocessing unit (GPU), a hardware processor core, or any combinationthereof), a main memory 804, a static memory 806, instructions 824,display device 810, input device 812, UI navigation device 814, massstorage 816, signal generation 818, output controller 828, NAV timers829, sensors 821, network interface device 820, and antennas 860 some orall of which may communicate with each other via an interlink (e.g.,bus) 808. One or more of the following of the apparatus of the machine800 may be separate from the machine 800 and may be configured to workin conjunction with the machine 800, or be a portion or component of themachine 800: a hardware processor (e.g., a central processing unit(CPU), a graphics processing unit (GPU), a hardware processor core, orany combination thereof), a main memory, a static memory, instructions,display device, input device, UI navigation device, mass storage, signalgeneration, output controller, NAV timers, sensors, network interfacedevice, and antennas. The apparatus of the machine 800 may be configuredto perform one or more of the methods or functions described herein.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 800 and that cause the machine 800 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding or carrying data structures used by or associated withsuch instructions. Non-limiting machine readable medium examples mayinclude solid-state memories, and optical and magnetic media. Specificexamples of machine readable media may include: non-volatile memory,such as semiconductor memory devices (e.g., Electrically ProgrammableRead-Only Memory (EPROM), Electrically Erasable Programmable Read-OnlyMemory (EEPROM)) and flash memory devices; magnetic disks, such asinternal hard disks and removable disks; magneto-optical disks; RandomAccess Memory (RAM); and CD-ROM and DVD-ROM disks. In some examples,machine readable media may include non-transitory machine readablemedia. In some examples, machine readable media may include machinereadable media that is not a transitory propagating signal.

The instructions 824 may further be transmitted or received over acommunications network 826 using a transmission medium via the networkinterface device 820 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others.

In an example, the network interface device 820 may include one or morephysical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or moreantennas to connect to the communications network 826. In an example,the network interface device 820 may include one or more antennas 860 towirelessly communicate using at least one of single-inputmultiple-output (SIMO), multiple-input multiple-output (MIMO), ormultiple-input single-output (MISO) techniques. In some examples, thenetwork interface device 820 may wirelessly communicate using MultipleUser MIMO techniques. The term “transmission medium” shall be taken toinclude any intangible medium that is capable of storing, encoding orcarrying instructions for execution by the machine 800, and includesdigital or analog communications signals or other intangible medium tofacilitate communication of such software.

Various embodiments may be implemented fully or partially in softwareand/or firmware. This software and/or firmware may take the form ofinstructions contained in or on a non-transitory computer-readablestorage medium. Those instructions may then be read and executed by oneor more processors to enable performance of the operations describedherein. The instructions may be in any suitable form, such as but notlimited to source code, compiled code, interpreted code, executablecode, static code, dynamic code, and the like. Such a computer-readablemedium may include any tangible non-transitory medium for storinginformation in a form readable by one or more computers, such as but notlimited to read only memory (ROM); random access memory (RAM); magneticdisk storage media; optical storage media; flash memory, etc.

The following examples pertain to further embodiments. Example 1 is anapparatus of a wireless device including: memory; and processingcircuitry coupled to the memory, the processing circuitry configured to:encode a trigger frame including a resource allocation for one or morestations, where the trigger frame comprises a network allocation vector(NAV) duration; configure the wireless device to transmit the triggerframe to the one or more stations; and if a response frame is notreceived from the one or more stations in response to the trigger framebefore a trigger frame timeout duration, configure the wireless deviceto contend for the wireless medium a first time, encode a retransmissionof the trigger frame, and configure the wireless device to transmit theretransmission of the trigger frame to the one or more stations.

In Example 2, the subject matter of Example 1 optionally includes wherethe processing circuitry is further configured to: configure thewireless device to contend for the wireless medium a second time priorto the contending for the wireless medium the first time; encode acontention-free (CF) end; and configure the wireless device to transmitthe CF end.

In Example 3, the subject matter of any one or more of Examples 1-2optionally include where the processing circuitry is further configuredto: encode a contention-free (CF) end prior to contending for thewireless medium the first time; and configure the wireless device totransmit the CF end.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include where the processing circuitry is further configuredto: if the NAV duration is greater than a threshold, contend for thewireless medium a second time prior to contending for the wirelessmedium the first time; encode a contention-free (CF) end; and configurethe wireless device to transmit the CF end.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include where the processing circuitry is further configuredto: if the NAV duration is greater than a threshold, encode acontention-free (CF) end prior to contending for the wireless medium thefirst time; configure the wireless device to transmit the CF end.

In Example 6, the subject matter of any one or more of Examples 1-5optionally include where the processing circuitry is further configuredto: if the trigger frame is to be transmitted within a transmissionopportunity (TXOP), and a remaining duration of a limit of the TXOP isgreater than a threshold, contend for the wireless medium, encode aretransmission of the trigger frame, and configure the wireless deviceto transmit the retransmission of the trigger frame to the one or morestations.

In Example 7, the subject matter of Example 6 optionally includes wherethe processing circuitry is further configured to: contend for thewireless medium by determining that the wireless medium is idle if at apoint coordination function (PCF) interframe space (PIFS) slot boundarythe wireless medium is idle.

In Example 8, the subject matter of any one or more of Examples 1-7optionally include where the processing circuitry is further configuredto: if the trigger frame is to be transmitted within a transmissionopportunity (TXOP) after a second trigger frame or another type of framethat initiated the TXOP, and a remaining duration of a limit of the TXOPis less than a threshold, contend for the wireless medium, encode acontention-free (CF) end, and configure the wireless device to transmitthe CF end.

In Example 9, the subject matter of any one or more of Examples 1-8optionally include where the processing circuitry is further configuredto: if the trigger frame is to be transmitted within a transmissionopportunity (TXOP) after a frame that initiated the TXOP, and aremaining duration of a limit of the TXOP is less than a threshold,encode a contention-free (CF) end, and configure the wireless device totransmit the CF end.

In Example 10, the subject matter of any one or more of Examples 1-9optionally include where the processing circuitry is further configuredto: if the trigger frame is to be transmitted within a transmissionopportunity (TXOP), and a remaining duration of a limit of the TXOP isless than a threshold, configure the wireless device to refrain fromtransmitting until the end of the limit of the TXOP.

In Example 11, the subject matter of any one or more of Examples 1-10optionally include where the trigger frame timeout duration is based onwhether the trigger frame is a multi-user request-to-send (MU-RTS) oranother type of trigger frame.

In Example 12, the subject matter of any one or more of Examples 1-11optionally include where the trigger frame is to initiate a transmissionopportunity.

In Example 13, the subject matter of any one or more of Examples 1-12optionally include where the trigger frame is one from the followinggroup: multi-user (MU) block acknowledgement request (BARXMU-BAR)trigger frame, MU request-to-send (RTS) (MU-RTS) trigger frame,beamforming request trigger frame, a beamforming report poll triggerframe, and MU uplink (UL) data trigger frame.

In Example 14, the subject matter of any one or more of Examples 1-13optionally include where the wireless device and the one or morestations are each one from the following group: an Institute ofElectrical and Electronic Engineers (IEEE) 14 is missing parent: 14 ismissing parent: 802.11ax access point, an IEEE 802.11ax station, an IEEE14 is missing parent: 14 is missing parent: 802.11 station, and an IEEE802.11 access point.

In Example 15, the subject matter of any one or more of Examples 1-14optionally include transceiver circuitry coupled to the processingcircuitry.

Example 16 is a non-transitory computer-readable storage medium thatstores instructions for execution by one or more processors, theinstructions to configure the one or more processors to cause a wirelessdevice to: encode a trigger frame including a resource allocation forone or more stations, where the trigger frame comprises a networkallocation vector (NAV) duration; configure the wireless device totransmit the trigger frame to the one or more stations; and if a frameis not received from the one or more stations in response to the triggerframe before a trigger frame timeout duration, configure the wirelessdevice to contend for the wireless medium a first time, encode aretransmission of the trigger frame, and configure the wireless deviceto transmit the retransmission of the trigger frame to the one or morestations.

In Example 17, the subject matter of Example 16 optionally includeswhere the instructions further configure the one or more processors tocause the wireless device to: configure the wireless device to contendfor the wireless medium a second time prior to the contending for thewireless medium the first time; encode a contention-free (CF) end; andconfigure the wireless device to transmit the CF end.

Example 18 is a method performed by a wireless device, the methodincluding: encoding a trigger frame including a resource allocation forone or more stations, where the trigger frame comprises a networkallocation vector (NAV) duration; configuring the wireless device totransmit the trigger frame to the one or more stations; and if a frameis not received from the one or more stations in response to the triggerframe before a trigger frame timeout duration, configuring the wirelessdevice to contend for the wireless medium a first time, encoding aretransmission of the trigger frame, and configuring the wireless deviceto transmit the retransmission of the trigger frame to the one or morestations.

In Example 19, the subject matter of Example 18 optionally includesconfigure the wireless device to contend for the wireless medium asecond time prior to the contending for the wireless medium the firsttime; encode a contention-free (CF) end; and configure the wirelessdevice to transmit the CF end.

Example 20 is an apparatus of a first wireless device including: memory;and processing circuitry coupled to the memory, the processing circuitryconfigured to: decode a trigger frame from a second wireless deviceincluding a network allocation vector (NAV) duration and a resourceallocation for each of one or more stations, and where the firstwireless device is not indicated in the trigger frame; set a NAV of thewireless device based on the NAV duration; and if no frame is detectedby the first wireless device, in a timeout duration, reset the NAV ofthe first wireless device, where the timeout duration is to start afterthe end of receiving the trigger frame.

In Example 21, the subject matter of Example 20 optionally includeswhere the timeout duration is determined based on whether the triggerframe is a multi-user request-to-send (MU-RTS) or another type oftrigger frame.

In Example 22, the subject matter of any one or more of Examples 20-21optionally include where the first wireless device is associated with asame basic service set (BSS) as the second wireless device or anoverlapping BSS (OBSS) of the second wireless device.

In Example 23, the subject matter of any one or more of Examples 20-22optionally include where the processing circuitry is further configuredto: decode a basic service set (BSS) color of the trigger frame, wherethe trigger frame comprises an high efficiency (HE) signal A field thatcomprises the BSS color; and if the BSS color indicates a differentcolor than a color of the first wireless device and a value of the BSScolor indicates that the first wireless device is to decode a mediaaccess control (MAC) portion of the trigger frame, decode the MACportion of the trigger frame.

Example 24 is an apparatus of a wireless device, the apparatusincluding: means for encoding a trigger frame including a resourceallocation for one or more stations, where the trigger frame comprises anetwork allocation vector (NAV) duration; means for configuring thewireless device to transmit the trigger frame to the one or morestations; and if a frame is not received from the one or more stationsin response to the trigger frame before a trigger frame timeoutduration, means for configuring the wireless device to contend for thewireless medium a first time, means for encoding a retransmission of thetrigger frame, and configure the wireless device to transmit theretransmission of the trigger frame to the one or more stations.

In Example 25, the subject matter of Example 24 optionally includesmeans for configuring the wireless device to contend for the wirelessmedium a second time prior to the contending for the wireless medium thefirst time; means for encoding a contention-free (CF) end; and means forconfiguring the wireless device to transmit the CF end.

In Example 26, the subject matter of any one or more of Examples 24-25optionally include means for encoding a contention-free (CF) end priorto contending for the wireless medium the first time; and means forconfiguring the wireless device to transmit the CF end.

In Example 27, the subject matter of any one or more of Examples 24-26optionally include if the NAV duration is greater than a threshold,means for contending for the wireless medium a second time prior tocontending for the wireless medium the first time; means for encoding acontention-free (CF) end; and means for configuring the wireless deviceto transmit the CF end.

In Example 28, the subject matter of any one or more of Examples 24-27optionally include if the NAV duration is greater than a threshold, thenbefore the contend for the wireless medium, means for encoding acontention-free (CF) end; and means for configuring the wireless deviceto transmit the CF end.

In Example 29, the subject matter of any one or more of Examples 24-28optionally include if the trigger frame is to be transmitted within atransmission opportunity (TXOP), and a remaining duration of a limit ofthe TXOP is greater than a threshold, means for contending for thewireless medium, means for encoding a retransmission of the triggerframe, and means for configuring the wireless device to transmit theretransmission of the trigger frame to the one or more stations.

In Example 30, the subject matter of Example 29 optionally includesmeans for contending for the wireless medium by determining that thewireless medium is idle if at a point coordination function (PCF)interframe space (PIFS) slot boundary the wireless medium is idle.

In Example 31, the subject matter of any one or more of Examples 24-30optionally include if the trigger frame is to be transmitted within atransmission opportunity (TXOP) after a second trigger frame or anothertype of frame that initiated the TXOP, and a remaining duration of alimit of the TXOP is less than a threshold, means for contending for thewireless medium, means for encoding a contention-free (CF) end, andmeans for configuring the wireless device to transmit the CF end.

In Example 32, the subject matter of any one or more of Examples 24-31optionally include if the trigger frame is to be transmitted within atransmission opportunity (TXOP) after a frame that initiated the TXOP,and a remaining duration of a limit of the TXOP is less than athreshold, means for encoding a contention-free (CF) end, and means forconfiguring the wireless device to transmit the CF end.

In Example 33, the subject matter of any one or more of Examples 24-32optionally include if the trigger frame is to be transmitted within atransmission opportunity (TXOP), and a remaining duration of a limit ofthe TXOP is less than a threshold, means for configuring the wirelessdevice to refrain from transmitting until the end of the limit of theTXOP.

In Example 34, the subject matter of any one or more of Examples 24-33optionally include where the trigger frame timeout duration is based onwhether the trigger frame is a multi-user request-to-send (MU-RTS) oranother type of trigger frame.

In Example 35, the subject matter of any one or more of Examples 24-34optionally include where the trigger frame is to initiate a transmissionopportunity.

Example 36 is a non-transitory computer-readable storage medium thatstores instructions for execution by one or more processors, theinstructions to configure the one or more processors to cause a wirelessdevice to: decode a trigger frame from a second wireless deviceincluding a network allocation vector (NAV) duration and a resourceallocation for each of one or more stations, and where the firstwireless device is not indicated in the trigger frame; set a NAV of thewireless device based on the NAV duration; and if no frame is detectedby the first wireless device, in a timeout duration, reset the NAV ofthe first wireless device, where the timeout duration is to start afterthe end of receiving the trigger frame.

In Example 37, the subject matter of Example 36 optionally includeswhere the timeout duration is determined based on whether the triggerframe is a multi-user request-to-send (MU-RTS) or another type oftrigger frame.

In Example 38, the subject matter of any one or more of Examples 36-37optionally include where the first wireless device is associated with asame basic service set (BSS) as the second wireless device or anoverlapping BSS (OBSS) of the second wireless device.

In Example 39, the subject matter of any one or more of Examples 36-38optionally include where the instructions further configure the one ormore processors to cause a wireless device to: decode a basic serviceset (BSS) color of the trigger frame, where the trigger frame comprisesan high efficiency (HE) signal A field that comprises the BSS color; andif the BSS color indicates a different color than the first wirelessdevice and a value of the BSS color indicates that the first wirelessdevice is to decode a media access control (MAC) portion of the triggerframe, decode the MAC portion of the trigger frame.

Example 40 is a method performed by a wireless device, the methodincluding: decoding a trigger frame from a second wireless deviceincluding a network allocation vector (NAV) duration and a resourceallocation for each of one or more stations, and where the firstwireless device is not indicated in the trigger frame; setting a NAV ofthe wireless device based on the NAV duration; and if no frame isdetected by the first wireless device, in a timeout duration, resettingthe NAV of the first wireless device, where the timeout duration is tostart after the end of receiving the trigger frame.

In Example 41, the subject matter of Example 40 optionally includeswhere the timeout duration is determined based on whether the triggerframe is a multi-user request-to-send (MU-RTS) or another type oftrigger frame.

In Example 42, the subject matter of any one or more of Examples 40-41optionally include where the first wireless device is associated with asame basic service set (BSS) as the second wireless device or anoverlapping BSS (OBSS) of the second wireless device.

In Example 43, the subject matter of any one or more of Examples 40-42optionally include the method further including: decoding a basicservice set (BSS) color of the trigger frame, where the trigger framecomprises an high efficiency (HE) signal A field that comprises the BSScolor; and if the BSS color indicates a different color than the firstwireless device and a value of the BSS color indicates that the firstwireless device is to decode a media access control (MAC) portion of thetrigger frame, decoding the MAC portion of the trigger frame.

Example 44 is a apparatus of a wireless device, the apparatus including:means for decoding a trigger frame from a second wireless deviceincluding a network allocation vector (NAV) duration and a resourceallocation for each of one or more stations, and where the firstwireless device is not indicated in the trigger frame; means for settinga NAV of the wireless device based on the NAV duration; and if no frameis detected by the first wireless device, in a timeout duration, meansfor resetting the NAV of the first wireless device, where the timeoutduration is to start after the end of receiving the trigger frame.

In Example 45, the subject matter of Example 44 optionally includeswhere the timeout duration is determined based on whether the triggerframe is a multi-user request-to-send (MU-RTS) or another type oftrigger frame.

In Example 46, the subject matter of any one or more of Examples 44-45optionally include where the first wireless device is associated with asame basic service set (BSS) as the second wireless device or anoverlapping BSS (OBSS) of the second wireless device.

In Example 47, the subject matter of any one or more of Examples 44-46optionally include the apparatus further including: means for decoding abasic service set (BSS) color of the trigger frame, where the triggerframe comprises an high efficiency (HE) signal A field that comprisesthe BSS color; and means for if the BSS color indicates a differentcolor than the first wireless device and a value of the BSS colorindicates that the first wireless device is to decode a media accesscontrol (MAC) portion of the trigger frame, decoding the MAC portion ofthe trigger frame.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

1. (canceled)
 2. An apparatus of a high-efficiency (HE) access point(AP), the apparatus comprising: memory; and, processing circuitrycoupled to the memory, the processing circuitry configured to: encode atrigger frame, the trigger frame comprising a type field indicating thetrigger frame is a multi-user request-to-send (MU-RTS) trigger frame,the trigger frame further comprising indications of HE stations tosolicit clear-to-send (CTS) frames to be transmitted by the HE stationsin response to the MU-RTS trigger frame, and the trigger frame furthercomprising a network allocation vector (NAV) duration, the NAV durationindicating a transmission opportunity (TXOP) duration of a TXOP;configure the HE AP to transmit the MU-RTS trigger frame, the MU-RTStrigger frame to initiate the TXOP; if a physical (PHY) receive (RX)start (PHY-RXSTART).indication primitive is not received before atimeout duration of a short interframe space time (SIFSTime)+a slot time(aSlotTime)+aRxPHYStartDelay after transmission of the MU-RTS triggerframe, determine that the transmission of the MU-RTS trigger frame hasfailed; and if the transmission of the MU-RTS trigger frame has failed,and if the TXOP was initiated, configure the HE AP to invoke a backoffprocedure at an PHY-RXEND.indication primitive.
 3. The apparatus ofclaim 2, wherein the processing circuitry is further configured to: if aPHY-RXSTART.indication primitive is received before the timeoutduration, wait for a corresponding PHY-RXEND.indication primitive, andif a clear-to-send (CTS) frame is received from one of the HE stationsbefore the corresponding PHY-RXEND.indication primitive, determine thetransmission of the MU-RTS trigger frame was successful; and if anotherframe is received before the corresponding PHY-RXEND.indicationprimitive, determine that the transmission of the MU-RTS trigger framehas failed.
 4. The apparatus of claim 2, wherein the timeout durationbegins after a PHY-TXEND.confirm primitive is received for transmittingthe MU-RTS trigger frame.
 5. The apparatus of claim 2, wherein the TXOPduration is set to a duration extending to an end of a transmission of amulti-station block acknowledgement.
 6. The apparatus of claim 2,wherein aRxPHYStartDelay indicates a delay duration for the HE AP toreceive the PHY-RXSTART.indication primitive.
 7. The apparatus of claim2, wherein the processing circuitry is further configured to: encodeanother trigger frame, the another trigger frame comprising another typefield indicating the another trigger frame is another MU-RTS triggerframe, and the trigger frame further comprising indications of the HEstations to solicit CTS frames to be transmitted by the HE stations inresponse to the another MU-RTS trigger frame;
 8. The apparatus of claim7, wherein the processing circuitry is further configured to: after thebackoff procedure has gained access to a channel, configure the HE AP totransmit the another MU-RTS trigger frame.
 9. The apparatus of claim 2,wherein the processing circuitry is further configured to: if aremaining TXOP duration is below a threshold, encode a contention-free(CF) end, and after the backoff procedure has gained access to achannel, configure the HE AP to transmit the CF end.
 10. The apparatusof claim 2, wherein the processing circuitry is further configured to:encode a contention-free (CF) end; and after the backoff procedure hasgained access to a channel, configure the HE AP to transmit the CF end.11. The apparatus of claim 2, wherein the processing circuitry isfurther configured to: if a remaining TXOP duration is above athreshold, encode another trigger frame, the another trigger framecomprising another type field indicating the another trigger frame isanother MU-RTS trigger frame, and the trigger frame further comprisingindications of the HE stations to solicit CTS frames to be transmittedby the HE stations in response to the another MU-RTS trigger frame, andafter the backoff procedure has gained access to a channel, configurethe HE AP to transmit the another MU-RTS trigger frame.
 12. Theapparatus of claim 2, wherein the processing circuitry is furtherconfigured to: invoke the backoff procedure by determining whether achannel is idle for a point coordination function (PCF) interframe space(PIFS) slot duration; in response to a determination that the channel isidle for the PIFS slot duration, determine that the channel is idle; andin response to a determination that the channel is not idle during thePIFS slot duration, increase the PIFS slot duration by a multiple of thePIFS slot duration, and determine whether the channel is idle for themultiple of the PIFS slot duration.
 13. The apparatus of claim 2,wherein the backoff procedure is performed in accordance with EnhancedDistributed Channel Access Function (EDCAF).
 14. The apparatus of claim2 wherein the HE AP is configured to operate in accordance with at leastone from the following group: Institute of Electrical and ElectronicEngineers (IEEE) 802.11ax and IEEE 802.11.
 15. The apparatus of claim 2,further comprising a transceiver coupled to the processing circuitry;and further comprising one or more antennas coupled to the transceiver.16. A non-transitory computer-readable storage medium that storesinstructions for execution by one or more processors of an apparatus ofa high-efficiency (HE) access point (AP), the instructions to configurethe one or more processors to: encode a trigger frame, the trigger framecomprising a type field indicating the trigger frame is a multi-userrequest-to-send (MU-RTS) trigger frame, the trigger frame furthercomprising indications of HE stations to solicit clear-to-send (CTS)frames to be transmitted by the HE stations in response to the MU-RTStrigger frame, and the trigger frame further comprising a networkallocation vector (NAV) duration, the NAV duration indicating atransmission opportunity (TXOP) duration of a TXOP; configure the HE APto transmit the MU-RTS trigger frame, the MU-RTS trigger frame toinitiate the TXOP; if a physical (PHY) receive (RX) start(PHY-RXSTART).indication primitive is not received before a timeoutduration of a short interframe space time (SIFSTime)+a slot time(aSlotTime)+aRxPHYStartDelay after transmission of the MU-RTS triggerframe, determine that the transmission of the MU-RTS trigger frame hasfailed; and if the transmission of the MU-RTS trigger frame has failed,and if the TXOP was initiated, configure the HE AP to invoke a backoffprocedure at an PHY-RXEND.indication primitive.
 17. The non-transitorycomputer-readable storage medium of claim 15, wherein the instructionsfurther configure the one or more processors to: if aPHY-RXSTART.indication primitive is received before the timeoutduration, wait for a corresponding PHY-RXEND.indication primitive, andif a clear-to-send (CTS) frame is received from one of the HE stationsbefore the corresponding PHY-RXEND.indication primitive, determine thetransmission of the MU-RTS trigger frame was successful; and if anotherframe is received before the corresponding PHY-RXEND.indicationprimitive, determine that the transmission of the MU-RTS trigger framehas failed.
 18. The non-transitory computer-readable storage medium ofclaim 15, wherein the timeout duration begins after a PHY-TXEND.confirmprimitive is received for transmitting the MU-RTS trigger frame.
 19. Anapparatus of a high-efficiency (HE) station (STA), the apparatuscomprising: memory; and, processing circuitry coupled to the memory, theprocessing circuitry configured to: decode a trigger frame, the triggerframe comprising a type field indicating the trigger frame is amulti-user request-to-send (MU-RTS) trigger frame, the trigger framefurther comprising indications of HE stations to solicit clear-to-send(CTS) frames to be transmitted by the HE stations in response to theMU-RTS trigger frame, and the trigger frame further comprising a networkallocation vector (NAV) duration, the NAV duration indicating atransmission opportunity (TXOP) duration of a TXOP, wherein the MU-RTSdoes not indicate the HE STA; set a NAV of the HE STA based on the NAVduration; and if no frame is detected by the HE STA in a timeoutduration, reset the NAV of the HE STA, wherein the timeout duration isto start after the end of receiving the MU-RTS trigger frame, whereinthe timeout duration is (2×a short interframe space (SIFS)Time(aSIFSTime))+(CTS Time)+a receive (Rx) physical (PHY) Start Delay(aRxPHYStartDelay)+(2×aSlotTime), and wherein the timeout durationbegins after a PHY-RXEND.indication corresponding to an end of thereception of the MU-RTS trigger frame.
 20. The apparatus of claim 19,wherein the processing circuitry is further configured to: decode abasic service set (BSS) color of the MU-RTS trigger frame, wherein theMU-RTS trigger frame comprises an high efficiency (HE) signal A fieldthat comprises the BSS color; and if the BSS color indicates a differentcolor than a color of the HE STA, decode the MAC portion of the MU-RTStrigger frame.
 21. The apparatus of claim 19, further comprising atransceiver coupled to the processing circuitry; and further comprisingone or more antennas coupled to the transceiver.